1. Field of Invention
The invention relates to an aquarium and, in particular, to the structure of an aquarium.
2. Related Art
A conventional aquarium, as shown in FIG. 4, has a filter 8 above the opening of its cultivating tank 7. The filter 8 has a water inlet pipe 81 and a water outlet pipe 82. When the filter 8 operates, the water inlet pipe 81 draws water in the cultivating tank 7 into the filter 8 for filtering. The filtered water is sent via the water outlet pipe 81 back into the cultivating tank 7. Such a cyclic operation achieves the goal of filtering the water.
However, the above-mentioned filtering method for the conventional aquarium mainly filters the water above the sand layer 84 of the cultivating tank 7. Since no water flows through the sand layer 84, it is impossible to filter water in the sand layer 84. Moreover, after the sand layer 84 of the cultivating tank 7 is used for some time, it is accumulated with a huge amount of pollutants such as animal excretions and residual food. They will produce extra poisonous ammonia or nitrous acid. It will deteriorate the water and endanger the animal's health.
Please refer to FIG. 5. It shows the structure of an aquarium 9 proposed by the inventor to solve the filtering problem in the prior art. It has been granted with ROC Pat. No. I288607. The top of the cultivating tank 9 is disposed with a water outlet 91. A dividing board 92 is disposed in the cultivating tank 9 so that the cultivating tank 9 is divided into a first accommodating tank 93 and a second accommodating tank 94. A water inlet pipe 95 draws clean water from an external source into the first accommodating tank 93 of the cultivating tank 9. In this case, the water from the external source flows from the first accommodating tank 93 into the sand layer 97 in the second accommodating tank 94 via the through holes 96 on the dividing board 92. Such a water current brings the impurities in the sand layer 97 toward the second accommodating tank 94 of the cultivating tank 9. Finally, the water leaves from the water outlet pipe 91 at the top of the cultivating tank 9. As a result, the excretions or impurities in the sand layer 97 can be washed out of the cultivating tank 9 by the current instead of accumulating therein. Moreover, when it is used in large aquaria or tanks, the water quality can be kept so stable that animals therein have a higher survival rate. Nevertheless, small aquaria have less water. Even after filtering, the water quality is still unstable. Therefore, how to effectively remove or decompose animal's excretions or residual food to ensure the water quality is the goal of the invention.